The present invention relates to a target excavating-surface setting system for an excavating machine, such as a hydraulic excavator, which is employed to set work conditions of the excavating machine, a storage medium storing a target excavating-surface setting program for an excavating machine, and a display device for use in the target excavating-surface setting system.
In a hydraulic excavator, an operator operates front members, such as a boom, by associated manual control levers. There is however a difficulty for the operator to judge whether or not excavation is carried out precisely along a ditch at a predetermined depth or a slope at a predetermined gradient, just by visually observing the front operation. It is therefore known to set the depth of an excavating surface or the gradient of a slope beforehand, and to perform automatic excavation control so that the set depth or gradient is achieved. A target excavating surface must be set to perform the automatic excavation control. A monitoring apparatus for an excavating machine disclosed in JP,A 62-185932 and an excavating machine disclosed in JP,A 5-287782 are proposed as employing a two-dimensional display device for setting a target excavating surface.
In the excavating machines disclosed in JP,A 62-185932 and JP,A 5-287782, a machine body and a target excavating surface are displayed in the form of pictures on a monitor, and a depth from the machine body to the target excavating surface or a gradient of the target excavating surface is also displayed on the monitor.
Further, an excavation area setting system for area limiting excavation control in construction machines, disclosed in, e.g., JP,A 9-53253, proposes a system in which an external reference, such as a leveling string or a laser reference surface formed by a laser lighthouse installed outside a machine body, is used in combination with a hydraulic excavator, and excavation is carried out continuously over a long distance along a surface at a certain depth or gradient relative to the external reference.
In the excavation area setting system disclosed in JP,A 9-53253, a laser beam receiver is attached to a front member, and a vertical shift upon travel of the machine body is compensated for with the aid of a laser beam so that a continuous linear excavating surface is obtained. Also, in that excavation area setting system, the relationship between the machine body and a target excavating surface is set by setting the target excavating surface relative to the laser reference surface.
In the excavating machines disclosed in JP,A 62-185932 and JP,A 5-287782, however, any external reference is not used. This means that display of an external reference is neither provided nor intended.
Also, the excavation area setting system disclosed in JP,A 9-53253 has a problem that a setting error is apt to occur because the depth, set by a setting device, from the laser reference surface (external reference) to the target excavating surface is displayed just in the form of a numerical value on the monitor.
More specifically, in a system employing a laser reference surface (external reference), excavation is carried out continuously over a long distance along a surface at a predetermined depth from the external reference such as the laser reference surface and, to this end, setting of a target excavating surface must be repeated using the external reference. In order to realize precise setting, therefore, it is required that the operator can confirm and recognize not only the positional relationship between a machine body and the target excavating surface, but also the positional relationship between the laser reference surface and the target excavating surface. In the conventional system wherein only a numerical value or only the positional relationship between the machine body and the target excavating surface is displayed, it is difficult for the operator to visually recognize the positional relationship between the laser reference surface and the target excavating surface, and hence a setting error is apt to occur.
An object of the present invention is to provide a target excavating-surface setting system for an excavating machine, which can easily set a target excavating surface using an external reference when excavation is carried out continuously over a long distance along a surface at a predetermined depth, and which is less apt to cause a setting error relative to the external reference, as well as to a storage medium and a display device for use in the target excavating-surface setting system.
(1) To achieve the above object, the present invention provides a target excavating-surface setting system for an excavating machine, in which a target excavating surface is set parallel to an external reference installed outside a machine body and a front device is controlled for the target excavating surface, thereby carrying out excavation continuously along the target excavating surface, wherein the system comprises input means for setting the target excavating surface; detecting means for detecting status variables relating to a position and a posture of the front device; first computing means for computing positional relationships among the body, the external reference and the target excavating surface by using signals from the input means and the detecting means; and second computing means for executing picture processing by using the positional relationships computed by the first computing means, and producing and outputting picture signals to display the positional relationships among the body, the external reference and the target excavating surface.
With the features set forth above, the positional relationships among the external reference, the target excavating surface and the body are displayed on image display means. By looking at the display, therefore, an operator can visually confirm and recognize non only the positional relationship between the body and the target excavating surface, but also the positional relationship between the external reference and the target excavating surface, and can ascertain whether the setting conditions are proper or not. As a result, the target excavating surface can be easily set using the external reference when excavation is carried out continuously over a long distance until and along a surface at a predetermined depth and a setting error is less apt to occur.
(2) In the above (1), preferably, the first computing means comprises first means for computing the positional relationship of the body relative to the external reference by using the signals from the detecting means; and second means for computing the positional relationship between the external reference and the target excavating surface by using at least the signals from the input means.
(3) Also, in the above (1), preferably, the input means includes numerical value input means for inputting a depth from the external reference to the target excavating surface, and the first computing means comprises third computing means for computing the positional relationship between the body and the external reference by using the signals supplied from the detecting means when the front device is in a predetermined positional relationship relative to the external reference; and first setting means for setting the positional relationship between the external reference and the target excavating surface by using the signals from the numerical value input means.
(4) In the above (3), preferably, the first computing means further comprises fourth computing means for computing the positional relationship between the body and the target excavating surface by using values computed by the third computing means and a value set by the first setting means, and the second computing means comprises first transforming means for executing processing to transform the values computed by the third computing means into values on a monitor coordinate system set for a display section of a display device on the basis of the body, and to display the positional relationship between the body and the external reference on the display section; and second transforming means for executing processing to transform values computed by the fourth computing means into values on the monitor coordinate system on the basis of the body, and to display the positional relationship between the body and the target excavating surface on the display section.
(5) Further, in the above (1), the input means may include direct-teaching instructing means operated when a work implement provided as the front device is at a predetermined depth. In this case, the first computing means comprises fourth computing means for computing the positional relationship between the body and the target excavating surface by using the signals supplied from the detecting means when the direct-teaching instructing means is operated; fifth computing means for computing the positional relationship between the body and the external reference by using the signals supplied from the detecting means when the front device is in a predetermined positional relationship relative to the external reference; and sixth computing means for computing the positional relationship between the external reference and the target excavating surface by using values computed by the fourth and fifth computing means.
(6) In the above (5), preferably, the first computing means further comprises seventh computing means for computing the positional relationship between the body and the target excavating surface by using values computed by the fifth and sixth computing means, and the second computing means comprises first transforming means for executing processing to transform the values computed by the fifth computing means into values on a monitor coordinate system set for a display section of a display device on the basis of the body, and to display the positional relationship between the body and the external reference on the display section; and second transforming means for executing processing to transform the values computed by the fourth computing means or the seventh computing means into values on the monitor coordinate system on the basis of the body, and to display the positional relationship between the body and the target excavating surface on the display section.
(7) Further, in the above (1), preferably, the input means includes means for setting a gradient of the external reference, the first computing means computes the positional relationships among the body, the external reference and the target excavating surface, including a set value of the gradient, and the second computing means produces the picture signals for displaying the external reference and the target excavating surface depending on the gradient.
(8) Still further, in the above (1), the target excavating-surface setting system further comprises a display device for displaying, in accordance with the computed positional relationships, a picture representing the body and straight lines representing respectively the external reference and the target excavating surface by using the picture signals outputted from the second computing means.
(9) Still further, in the above (1), preferably, the first computing means is disposed in a first control unit, and the second computing means is disposed in a second control unit separate from the first control unit.
(10) To achieve the above object, the present invention also provides a storage medium storing a target excavating-surface setting program for an excavating machine, in which a target excavating surface is set parallel to an external reference installed outside a machine body and a front device is controlled for the target excavating surface, thereby carrying out excavation continuously along the target excavating surface, wherein the program operates a computer to execute the steps of computing positional relationships among the body, the external reference and the target excavating surface by using a signal from input means for setting the target excavating surface and signals from detecting means for detecting status variables relating to a position and a posture of the front device; and executing picture processing by using the computed positional relationships for producing and outputting picture signals to display the positional relationships among the body, the external reference and the target excavating surface.
(11) To achieve the above object, the present invention further provides a display device for use in a target excavating-surface setting program for an excavating machine, in which a target excavating surface is set parallel to an external reference installed outside a machine body and a front device is controlled for the target excavating surface, thereby carrying out excavation continuously along the target excavating surface, wherein the display device comprises a display section for taking in picture signals representing previously computed positional relationships among the body, the external reference and the target excavating surface, and displaying a picture representing the body and straight lines representing respectively the external reference and the target excavating surface in accordance with the previously computed positional relationships.